1. Field of the Invention
The present invention relates to the field of equipment for driving a pile member, and more particularly to a hammer for driving a pile member and to a method for producing a reciprocating impact load against a pile member, and moreover to a method for producing a reciprocating impact load against a pile member, which is to be driven from an offshore installation.
In the pile driving equipment field, as in many other fields, there is always a need for equipment which has a high degree of adaptability. For example, it is more desirable to have a pile driving hammer which functions just as effectively in driving a pile member from an offshore installation as it does in driving a pile member on land, than it is to have a pile driving hammer which is more effective in one mode of operation than in the other, thus possibly requiring different pile driving hammers.
It would therefore be desirable to those in the pile driving equipment art, to have available to them a pile driving hammer which is highly adaptable, for example, which can be utilized just as effectively in driving pile members at onshore as well as offshore sites. The present invention fulfills such a need.
Also important to those interested in the field of pile driving equipment are reliability and efficiency. A pile driving hammer which has a high downtime due to wear, maintenance and the like, is quite naturally undesirable. Just as undesirable is a pile driving hammer which does not have a high rated striking force. Accounting for these deficiencies results in higher costs with a consequent reduction in competitiveness.
It would therefore be desirable to those in the pile driving equipment art to have available to them a pile driving hammer which has a low downtime and which provides a high rated striking force. The present invention provides such a pile driving hammer.
2. Description of the Prior Art
I am aware of two recently issued patents to Steven V. Cherminski relating to a pile driving hammer and method which warrant comment. These are U.S. Pat. No. 3,714,789, issued on Feb. 6, 1973 and U.S. Pat. No. 3,788,402, issued Jan. 29, 1974. The hammer disclosed in these patents includes in its essential elements a piston assembly, a cylinder bottom, a bounce chamber, defined between the piston assembly and the cylinder bottom, a pressurized driving fluid storage chamber formed in the cylinder bottom, a release valve, which controls communication between the bounce chamber and the storage chamber, and a pile driving adapter. There are five different modes of operation disclosed in these patents, all of which include energizing the bounce chamber from the storage chamber in order to displace the piston assembly away from the cylinder bottom, with one of these modes including preloading and impacting. However, it should be noted that in this mode, as in the other modes, there is no displacement of the anvil structure before impacting. It is doubtful that such a system, which is structurally and functionally different from the present invention, with the problem of metal fatigue, which inevitably would result from the mode described, would provide the state of the art with an answer to the needs expressed above.